Gun training mechanism



July 8, 1958 K. CLARK 2,841,887'

GUN TRAINING MECHANISM original Filed May 9, 1945 sheets-sheet 1INVENTOR. Kum. Lwk

July 8, 1958 K. CLARK 2,841,887

GUN TRAINING MECHANISM Original Filed May 9, 1945 6 Sheets-Sheet 2 YJuly8, 1958 K CLARK GUN TRAINING MECHANISM 6 Sheets-Sheet 5 Uriginal FiledMay 9, 1945 July 8 1958 i K. CLARK 2,841,887

GUN vTRAINING MECHANISM Y Original Filed May 9. -1945 6 Sheets-Sheet 4INVENTOR- Kem QU Chkrk July 8, 1958 K. CLARK 2,841,887

GUN TRAINING NECHANISM original Filed May 9, 19:15 s sheets-sheet 5 Komi n 'INVENTOR CMYK July 8, 1958 K. CLARK GUN TRAINING MECHANISM 6Sheets-Sheet 6 Original Filed May 9. 1945 United States GUN TRAININGMECHANISM Kendall Clark, Glen Ellyn, Ill.

3 Claims. (Cl. .3S-25) This invention relates to gun turrets andincludes a method of and apparatus for training gunners.

This application is a division of my copending application Serial No.592,765, led May 9, 1945 for Gun Training Mechanism, now Patent No.2,640,395, issued lune 2, 1953.

lt is an object of my invention to provide a training turret having acompensating gun sight and a moving target together with a means forsimulating the firing of the gun and recording the number of simulatedshots tired as well as the number of simulated shots which would havehit the target.

It is another object of my invention to provide an improved and moreresponsive mechanism for controlling the movement of a gun which willreduce hunting and which is applicable both to guns for trainingpurposes and to guns used in actual combat.

These objects are attained by providing a turret similar to the turretused for actual combat having compensating gun sight and gun simulatingmeans with a tiring contr-ol together with a movable target which may beautomatically or manually controlled and provided with a compensatingmeans in order to compute the proper direction of the gun upon thetarget. An improved form of continuously operating drive means tocontrol the movement of the gun in vertical and horizontal directionsispro vided with an initially effective manually operated acceleratingdevice to reduce hunting.

Further objects and advantages of the present invention will be apparentfrom the following description, ref erence beingrhad to the accompanyingdrawings wherein a preferred form of the present invention is clearlyshown.

Vin the drawings:

Figure 1 is a view in elevation of a training turret and target controlembodying one forni of my invention;

Figure 2 is a top view of the turret shown in Figure l;

Figure 3 is a fragmentary view of the turret with the target elevated toa 30 angle and the sight elevated to a angle;

Figure 4 is -a view in elevation of the gun moving drive unit which isapplicable both to theV training turret and to an actual combat turret;

Figure 5 is a side view of the drive unit shown in Figure 4 togetherwith a portion of the turret track, taken on the line` 5 5 of Figure 2;

Figure 6 is a small view of the speed adjusting pulley drive shown inFigures 4 and 5 illustrating the position of the drive for movement ofthe gun in one direction;

Figure 7 is a small view of the pulley drive positioned for holding thegun stationary;

Figure 8 is a small view of the pulley drive positioned for movement ofthe gun in the opposite direction;

Figure 9 is a horizontal sectional View of the drive unit shown inFigure 4 taken along 9-9a-9b of Figure 1G;

Figure 10 is a sectional view taken along the lines 10h10 of Figure 9;

ICC

Figure 1l is a view of a machine gun which may be used in pairs upon theturret shown in Figure 1 when used in actual combat.

Figure 12 is a front view of the compensating means for compensating forthe speed of movement of a target in order to accurately score thegunner;

Figure 13 is a sectional view taken along the line 13--13 of Figure 12;

Figure 14 is a sectional view taken along the lines 14-14 of Figure 12;

Figure l5 is a rear View of the gun moving and firing control; and

Figure 16 is a wiring diagram of the target control system, the targetcompensating system and the scoring system.

Referring now to the drawings and more particularly to Figures l to 3there is shown a square angle iron base 21 from the corners of whichfour or more struts 23 extend upwardly to support two stationary rings25 and 27 of channel iron, the webs of which are placed back to hackwith a space in between as shown in Figures 2 and 5. The channel ironrings 25 and 27, which may be made integral in the form of an l section,form a rigid stationary support in the form of two circular tracks orrings. The outer stationary track 2S is for the support of thetarget-carrying mechanism to be hereinafter described, and the innerstationary ring 27 is for the support of the turret or gun-carryingmechanism.

Target mechanism t Upon the outside of the stationary outer ring 25there supporting a pivot pin 39 providing a pivotal connection` with theU-shaped target support loop 41 which overlaps substantially one-halfthe circumference of the ring 29. The target 43 which may have theoutline of an aeroplane is provided at the middle point of the supportloop 41. The support loop 41 is provided with a pair of counter weights45 to correct its unbalance. The target support loop 41 is provided witha sector gear 49 driven by an electric motor 51 through a pinion gear53. The motor 51, which is supported by the bracket 52 fastened to themovable ring 29, has directly connected to it a small generator 55 thepurpose of which will be explained hereafter. The motor 51 drives apinion 53 in engagement with the sector gear 49 to elevate or lower thetarget 43. ln order to move the target horizontally, a second motor 57is provided with a gear reductionextending to a rubber tired roller 59in driving engagement with the lower face of the movable ring 29. Thismotor 57 is supported by the bracket 61 fastened to the stationary ring2S. The motor 57 is likewise coupled to a small generator 63 for apurpose to be explained hereafter.

The motors 51 and 57 are controlled manually by` the `remote targetcontrol 65 (Figure l) provided with a single vertical and lateralcontrol 67 in the form of a control stick which projects upwardly fromthe control box 69 which is provided with a universal type support (notshown) at the lower end of the stick. The target control 65 is connectedVby suitable flexible conductors in the flexible casing 71 with themotors 51 and 57 and by two flexible conductors in the flexible casing73 with a suitable source of power. The operation of the control 65 willbe explained hereafter in connection withFignre 16.

The turret housing yWithin the stationary inner ring 27 is a movablering of channel iron (Figures 2 and 5) which forms the main frame of theturret. This movable ring 75 is rotatably supported within thestationary ring 27 by the rollers which are rotatably mounted upon thestub shafts 122 supported by the flanged hubs 124 mounted upon themovable ring 75. Depending from the movable ring 75 is `a cylindrical:shell 77 which encloses the gunners portion of the turret and supportsthe licor 79. The movable ring 75 is provided with a transverse member81 which locates the vertical support members 83. These support members83 in turn carry a seat d5 for the gunner 87 indicated in Figure 1. Asupport 89 is also provided for the gunners feet. The cylindrical shellis open at the rear to permit entrance and exit of the gunner.

The gu'n mount The movable ring 75 is provided with a pair of brackets91 which pivotally support a gun yoke 93. Supported upon this gun yokeare a pair `of simulated guns 95 which may be of any -suitable type whenthe turret is used for training purposes. When the turret is used foractual combat or firing purposes, the pair of :simulated guns arereplaced by actual machine guns of any suitable type, an example ofwhich is shown in Figure 11. In order to elevate the gun yoke 93 and theguns 95 there are pivotally connected to the opposite sides of the yoke93 the links 97 which connect to a pair of sector gears 99 fastened to across rod 102 rotatably lsupported by the brackets 104 upon the` movablering 75. The sector gears 99 mesh with pinions 105 upon opposite ends-of the shaft 106 (Figure 2) which extends in opposite directions fromthe turret drive unit 1%. The turret drive unit 108 is supported by thebrackets 110 carried by the movable ring 75. lIn order to rotate theturret, the turret drive unit 108`is provided with -a hub 112, having abea-ring 114 (Figure 9) in its outer end. Protruding from this hub is ashaft 116 which carries a pinion 118 which is in driving engagement withVring gear 119 -upon the bottom face ofthe stationary ring 27, as bestshown in Figure 5. The rotation of this pinion 118 turns the `ring -andthe entire turret relative to the stationary ring 27. Instead of thepinion 118, a rubber tired roller -may be used in direct engagement withthe bottom face of the stationary ring 27. The ring gear 119 is thenomitted.

Gun control Referring to Figures 1, 2, 3 and 15, the gun and turretcontrol is provided with a pair of handles 126 to be clasped by thegunner for moving the gun both vertically and horizontally. One of thehandles is provided with trigger 128 for controlling the firing of theguns or any simulations thereof. As is best shown in Figure 15, thehandles 126 are connected together by a hollow boxshaped handle bar 130which may contain computing instruments for the sight 348, if desired.This handle bar 130 is supported by a universal joint connection 132upon a bracket 134 extending from the vertical supports 83.

The handle bar 130 is connected in its middle rear byV elevation controlrod 136 to the lever 138 -upon the end of the shaft 140 of the turretdrive unit 108 yas shown in Figures 2, 3, 4, and 5. This controls thegun elevating drive provided by the turret drive unit 108 through the`shaft 106 and the pinions y105 which mesh with the sector gears 99carryingthe links 97 which connect with the gun yoke 93. At one side,the handle bar 130 is connected by the azimuth control rod 142 with thelever 144 provided on the inner end of a shaft `146 (Figures 4 and 9) inthe control portion of the turret drive unit 108. The shaft 146 controlsthe rotation of the pinion 118 to rotate the turret.

The mechanism of the turret drive unit Referring now more particularlyto Figures 4 to 10 inclusive, it will be seen that the shaft 140 islocated in axial alignment with the shaft 146 directly beneath andparallel to the shaft 106 as shown in Figure 5. This shaft 140 protrudesfrom the outer end of the drive unit 108 and is provided with an arm 148carrying an idler A pulley 150 which is in contact with a V-belt 152.This V-belt 152 extends around a fixed pitch pulley 154 fixed to theshaft 156 protruding from the one end of the drive unit 108 and a spring.pressed variable ypitch pulley 158 fixed to one end of the drive `shaft159 of the double ended electric motor 160 supported by the bracket 162of the turret drive unit 108. This end of the motor shaft 159 also isprovided with the fixed pitch pulley 164 for driving by means of theV-belt 166 `a -fixed pitch V-belt pulley 168 of twice the pitch diameterof the pulley 164. This side of the turret drive unit is employed tocontrol the elevation or zenith movement of the gun.

Upon the opposite side of the turret drive unit 108, which controls thehorizontal or azimuth movement of the gun, the shaft 146 is provided atits outer end with an arm 170 carrying an idler pulley 172 which ismaintained in contact with the V-belt 174 extending around the fixedpitch pulley 176 and the variable pitch pulley 178 fixed to the end ofthe drive shaft 159 of the double ended electric motor 160. This pulley178 is provided with one flange 180 which is 4fixed to the end of themotor shaft and a second flange 182 which is slidably but nonrotatablymounted upon the motor shaft. This second flange 182 is resilientlyurgedV toward the fixed fiange 180 by the compression spring 184 locatedbetween the flange 182 and a smaller pulley 186 which is fastened to themotor shaft 159. The pulleys 158 and 178 are identical with theexception that the shaft ends and pulleys are reversed in position. Thefixed pitch pulley 186 through the V-belt 188 drives a fixed pitchpulley 190 of twice 'its pitch diameter.

The pitch diameter of the variable pitch pulleys 158 and 178 through theaction of the idler pulleys 150 and 172 are `varied for example from aratio in which the pitch diameter is three fourths the pitch diameter ofthe fixed pitch pulleys 154 yand 176, as illustrated in Figure 6, to aratio vwherein the pitch diameter of the pulleys 158 and 178 is one andone fourth times the pitch diameter of the fixed pitch pulleys 154 and176, as illustrated in Figure 8. This range of ratio may be increased ordiminished as required in order to provide a greater or lesser range ofspeed vari-ation. Y

The pulley. 176 is fixed to the shaft 192 to which is keyed a bevel gear194 meshing with a set of differential gears 196 which are freelyrotatably mounted upon the differential hub 198. The differential hub198 extends in the form of a sleeve concentrically mounted upon androtatable independently of the shaft 192 with the pulley fixed upon itsouter end. The foregoing elements together with the bevel gear 209constitute the first azimuth planetary system. The pulley 154 issimilarly connected through the shaft 156 to a beveled gear 203 whichmeshes with the freely rotatable differential gears 205 carried by thedifferential hub 207, which, similarly is rotatably mounted on shaft 156and carries a pulley 168, upon its outer end. The foregoing elementstogether with the bevel gear 221 constitute the first zenith planetarysystem.

The differential gears 196 mesh with a second beveled gear 209 having aspur gear 201 mounted directly thereon which forms the sun gear of asecond azimuth planetary system which includes the planet gears 211enmeshed with the sun gear 201 and ring gear 213. The planet gears 211are rotatably mounted upon a carriage 215 provided with a `sleeveextending to carry the bevel gear 217 which meshes with a bevel gear 219provided at the inner end of the azimuth shaft 116 which through thepinion on roller 118 rotates the turret. The second beveled gear 209,the spur gear 201 and the sleeve of the carriage 215 are all rotaablymounted on the shaft 192. On the other side of the unit used forelevating the guus, the differential gears 205 mesh with the bevel gear221 which has coupled directly to it the second zenith planetary systemwhich includes a sun gear 223 meshed with the planet gears 225 which inturn mesh with an internally toothed ring gear 227. The planet gears arecarried by a carriage 229 which in turn carries a. helical gear 231connected through an idler 233 with a helical gear 235 fixed to theshaft 106 which extends in opposite directions and is provided with thezenith or gun elevating gears 105 at its opposite ends of the turretdrive unit 108, as best shown in Figure 2. The bevel gear 221, the sungear 223 and the sleeve of the carriage 229 are all rotatably mounted onthe shaft 156.

With this construction, the turret rotating or azimuth drive lsectioncontains two planetary or epicyclic gear trains and likewise the gunelevating or zenith drive section contains two planetary or epicyclicgear trains. The first epicyclic gear train of each section is thatwhich includes the differential gears 196 for azimuth drive and 'thedifferential gears 205 for the zenth drive. It will be understood thatby this differential drive arrangement if the pulleys 16S and 154 turnat the same angular speed the differential is, in effect, locked and thebevel gear 221 turns at the same speed as the pulleys 16S and 154. Butif the pulley 154 turns at twice the angular speed of the pulley 168 asin Figure 7 then the bevel gear 221 will remain stationary and there isno movement of the zenith driving gear 105. This is true because thedifferential gears 205 rotate in the opposite direction with respect tothe gear 203 and therefore neutralize under these conditions therotation of the gear 2%3.

When as in Figure 6 the pulley 154 rotates at a speed between one andtwo times the speed of the pulley 16% the bevel gear 221 will be given arotational movement in the saine direction as the pulleys but at areduced speed which approaches zero as the pulleys approach a two to oneangular speed ratio. When as in Figure 8 the pulley 154 rotates morethan twice as fast as the pulley 168 the bevel gear 221 will turn in theopposite direction at a speed which will increase as the ratio increasesabove two to one. This type of drive is especially valuable for moving agun both in azimuth and in zenith since it is possible to keep the drivemotor and gearing rotating continuously so that it is instantlyavailable for moving the gun. it has the further advantage that themotor and connected gearing l have suicient rotational inertia so as tomalte the drive mechanism immediately responsive to the gunners control.

The second planetary or epicyclic gear train of the azimuth as well asthe zenith sections has two functions. One function is to provide speedreduction and the other function is to reduce hunting in training thegun sight upon the target.

When an operator endeavors to train a sight upon a moving target such asan aeroplane he must rst speed up the gun moving mechanism at a morerapid rate than the moving target'in order to catch up with the movingtarget. As the moving target comes within the field of sight it isnecessary to slow down the gun moving mechanism until equal to the speedof the moving target. This almost inevitably causes the overrunning ofthe target in the sight several times. In order to reduce this difcuityi provide means whereby, when the control for the driving mechanism ismoved to start movement ofthe gun, an additional accelerating force issuperimposed upon the turret drive unit. This provides an 6 especiallyrapid startY for the movement of the gun which quickly slows down sothat it follows the normal gun movement requirements of rapidlycatching; up with the target. This effect also provides a quick negativeacceleration or deceleration for slowing down to the speed of the targetwhen the target comes within the field of sight. This aids in reducingthe amount and frequency of overrunning the target. This positive andnegative acceleration effect is referred to as kick in the claims.

The mechanism for accomplishing this purpose is illustrated in figures 9`and 10. This is accomplished by fixing a forked arm 241 to the azimuthcontrol shaft 1&6 and a similar forked arm 243 to the zenith controlshaft 140. The forked arm 241 is provided with a slot 245 which engagesa pin 247 protruding from the ring gear ring gear 213 is thus heldstationary as long as the azimuth control shaft 146 is held stationary.In the second azimuth planetary system the three gear elements 211 and201 and 213 mutually react upon one another but when the ring gear 213is held stationary it takes the reaction, and the planet gears 211 thenrotate in direct proportion to the rotation of the sun gear 201; Thering gear 213 is therefore sometimes referred to as a normallystationary reactor element. As is shown best in Figure 10 the forked arm241 has a movement of nearly and is capable of moving the ring gear 213about 30 in either direction from the mid point of the arm 241. Thisinitial movement of the normally stationary ring gear 213 provides anadded rotation of the planet gear 211 and the bevel gears 217 and. 219and the turret drive gear 118 which provides the initial burst of speedwhich is very desirable in moving the gun when it is being trained uponthe target. Thus the movement of the ring gear 213 provides a movementof the planet gears 211 even though the sun gear 201 be stationary. lfthesungear 201 should be rotating at one speed to normally drive theplanet gears 211 at a second speed in direct proportion thereto,` themovement of the ring gear 213 will either increase or decrease the speedof the planet gears 211 from that second speed, depending upon whetherthe ring gear 213 is rotated in the same or opposite direction as therotation of the sun gear 201. For example, the ring gear 213 is rotatedin the same direcn tion as the sun gear 201 when it is desired to speedup the movement of the turret or the gun in any given direc tion Whilethe ring gear`213 is rotated in 'the direction opposite to the rotationof the sun gear when the movement is slowed down.

By this arrangement whenever the h-andle bar control is moved initiallyto start the operation of the azimuth drive section, the ring gear 213is moved in the direction of the desired movement an amount dependingupon and roughly proportioned to the speed that the operator desiredfrom the azimuth drive section. The corresponding mechanism for thezenith drive section is not shown but the forlred arm and thecooperating pin on the ring gear 227 are identical in construction andoperate in the same manner as described for the arm 241 and the pin 247and the ring gear 213.

Wiring diagramP-target moving portion Referring now to Figure 16, thereis shown the mov able contact arm 251 which is controlled by the foreand aft movement of the control 67 (Figure l) to lower or raise thetarget in its zenith movement, while the movable contact arm 255 iscontrolled by the lateral or left and right movement of the control 67to control the azimuth movement of the target to left and rightrespectively. The arm 251 taps a potentiometer coil 255 while the arm253 taps the potentiometer coil 257.` These coils 255 and 257 areconnected in parallel electric circuits across the direct current supplyconductors 259 `and 261 provided in the casing 73 (see Figure 1). Thecontact arm 251 is connected by the conductor 263 to the stationaryconductor ring 26S mounted on fixed ring 25 (see Figure 5) which isalways contacted by the contact 267 supported by the movable targetcarrying ring 29. This contact 267 is connected by the conductor 269 tothe commutator brush 271 of a direct current motor 51 which moves thetarget 43 in a vertical direction. The other commutator brush 273 isconnected by the conductor 275 to the movabie contact 277 of thepotentiometer coil 279. This potentiometer coil 279 is connected acrossthe supply conductors.

The supply conductors 261 and 259 are connected to the stationaryconductor rings 281 and 283 upon which ride the wiping contacts 285 and287 provided upon the movable target carrying ring 29. These contacts235 and 287 connect to the transmitting conductors 289 and 291 whichconnect to the electrical devices on the turret. The potentiometer coil279 is connected at one end through the conductors 293 and 295 to thetransmission conductor 291 and at the other end through the conductor297 to the transmission conductor 289. The field coils 299 of theelectric motor 51 are likewise connected by the conductors 302 and 304across the transmission conductors 289 and 291.

The motor 51 is provided with a shaft extension containing a worm 306 inoperating engagement with the worm gear 308 which drives the movablecontact arm 277 in such a direction that when current ows through thecommutator of the electric motor 51, the movable contact arm 277 will bemoved until it reaches a position where the current through thecommutator will be zero. In eiect, the potentiometer coil 255 forms thetwo resistances forming one branch of a Wheatstone bridge circuit whilethe potentiometer coil 279 forms the two resistances of the other branchof the Wheatstone bridge circuit. The proportioning of the tworesistances is provided by the movable contact arms 251 and 277 whichare connected through the brushes 271 and 273 of the electric motor 51to form the bridge of the Wheatstone bridge circuit in which the motor51 takes the place of the conventional galvanometer.

By this arrangement, when the control 67 moves the movable arm 251 toany desired position, the motor 51 will rotate to elevate the target 43(Figures 2 and 3) through the gear 53 and the sector gear 49 until themov- `able contact arm 277 moves to a point where the current throughthis circuit becomes zero.

The azimuth target control is similar to the zenith target control. Themovable contact arm 253 is connected by the conductor 312 to thestationary conductor ring 314 which is contacted by the wiping Contact316 I connected by the conductor 318 to the brush 320 of the azimuthdrive motor 57 which has its other brush 322 connected by the conductor324 to the movable contact arm 326. The movable contact arm 326 makescontact with the potentiometer coil 327. The potentiometer coil 327 aswell as the iield coil 330 of the motor 57 are connected in parallelelectric circuit relationship across the transmission conductors 289 and291. As in the zenith target control, the movement of the movablecontact 253 causes the motor 57 to move the movable contact arm 326 andthe target supporting loop 41 to a position wherein the current throughthis circuit becomes a zero. In this way the target is moved in azimuthand zenith, that is, horizontally and vertically in accordance with themovement of the control 67 which controls the position of the contactarms 251 `and 253.

Shot and hit computation system In order to count the number of shots,the gunner presses the trigger 128 which closes switch 328. The switch328 is connected through the conductor 329 and the wiping contact 330 tothe contact ring 281 which connects to the supply conductor 259. Theswitch 328 connects to the stationary contact 332 of a pulsator orinterruptor which includes an electromagnet coil 336 and an armature 334adapted to make contact with the contact 332 when -re- 8 tracted fromthe coil 336. The coil 336 is connected electrically to the armature andto the conductor 338 which connects through the wiping contact 340 withthe stationary ring 283 which connects to the supply conductor 261.

Ey this arrangement when the switch 328 is closed the pulsatorrepeatedly opens and closes the circuit. This is done by reason of thefact that when the armature 334 is in engagement with the contact 332,current will iiow through the electromagnet coil 336 and attract thearmature 334 to open the circuit. The opening of the circuit willdeenergize the coil 336 thereby allowing gravity or a spring to returnthe armature 334 in contact with the contact 332. This is so adjustedthat a number of circuit interruptions substantially equal the firingrate of the type of gun to be used with this style of target.

The interruptions corresponding to the shots which would be hred are'counted upon a meter 342 which is connected in electric parallelcircuit relationship with the electromagnet coil 336.

The hit computation system A simple addition to this circuit computesthe number of hits the gunner makes upon the target 43. This is providedby a switch 344 which is connected in the circuit which is arranged inparallel with the meter 342 and the electromagnet 336. This switch is sooperated that it is closed whenever the gunner properly trains the sightupon the target 43 as will hereinafter be explained. This switch 344controls the flow of current through this circuit which includes asecond meter 346 which -counts the impulses of current which flowthrough this parallel circuit when the switch 344 is closed. With thisarrangement the number of shots can readily be determined by inspectionof the meter 342 and the number of hits by inspection `of the meter 346.From this, the percentage of hits relative to the number of shots canreadily be determined. This provides the most important element indetermining the skill of the gunner undergoing training.

The operating means for the switch 344 is more complicated. The gunner87 is provided with a compensating gun sight 348 which may be a standardair craft gun sight or one for example such as is shown in the Patentset al. Patent 1,937,517. Such a sight will advance the Vgun a properamount ahead of the target viewed through the sight in order to-compensate for the speed of the target as well as the trajectory of thebullets and shells. This is provided for by the computer box 350 whichis mounted upon top of a turret drive unit 108 and is driven from thezenith drive through the helical gear 352 on the shaft 354 and from theazimuth drive by the helical gears 356 and 358 and the shaft 360. Thiscomputer box controls the sight 348 to provide the proper lead for thegun in advance of the sight upon the target.

The necessity of providing a lead for the gun in advance of the sightfor a training turret of this type may be questioned. However, this isdesirable in order to keep the gunnery trainee familiar in training indirecting compensated sights upon a target and experiencing the leadthat such a sight provides for the guns. Inasmuch as a lead is providedfor the gun and the entire turret in advance of the sight it is alsonecessary to compensate the counting mechanism to co-rrect for the speedof the target. The switch mechanism 344 therefore must have compensationfor the speed of the target.

The switch 344 proper is carried in a case at the end `of an arm 362(see Figure 2) extending from the gun yoke 93. Thus this arm moves inaccordance with the movement of the gun 95. The switch 344 has an`operating cam 364 projecting from it. When depressed this cam closesthe switch 344. In order to close the switch 344, I provide a cam 366which is mounted upon compensating'mechanism generally indicated by thereference character 368 and shown in detail in Figures l2, 13, 14

and 16. This compensating mechanism includes a bracketV 370 which isfastened to the target loop 41 provided with a post 372 for thispurpose. The bracket 370 carries a horizontal or azimuth compensatingmechanism which includes an electric motor 376 directly connected to ascrew 378 which is in threaded engagement with a slide 380. This slide380 is slidably mounted upon the rods 382 which have their end supports384 providing the bearing supports for the screw 378. This .structureprovides the azimuth `or horizontal compensation.

The zenith or vertical compensation is provided by the electric motor386 which` rotates the screw 383 which is threaded through the verticalslide 390 carrying the cam 366. The slide 390 is mounted upon the rods392 which terminate in the end support 394, one of which supports themotor 386. In addition to this mechanism, a potentiometer coil 396 (seeFigures 14 and 16) is carried oetween the bracket 382 and is contactedby the movable contact 398 fixed to the slide 380. Also a potentiometercoil 401 is carried between the bracket 390 and is contacted by themovable contact 403 carried by the slide 390.

As is best shown in the wiring diagram, Figure 16, the `ends of thepotentiometer coils 396 and 401 are connected across the transmissionconductors 289 and 291. The middle point of the coil 396 is connected bya conductor 405 to the commutator brush 407 of the generator y63 whichis coupled directly to the drive motor 57. The other commutator brush409 is connected by conductor 411 with the coil 413 of a polarized relay415. This polarized relay 415 has an armature 1or contact member 417which is connected at all times by conductor 419 to the transmissionconductor 289. The construction of this relay 415 is such that when nocurrent iiows through the coil 413 then the armature 417 will be at itsmiddle point and not be connected in a circuit. Whenever a current flowsthrough the coil 413 the armature 417 acting as a reversing switch willmake contact either with the conductor 421 or the conductor 423depending upon the direction of current ow. The conductor 421 connectst-o one set 425 of eld windings `of the reversible motor 376 and theconductor 423 connects to the other set 427 of the iield windings which,when energized, cause the motor 376 to rotate in the opposite direction.

There is a predetermined voltage drop however through the potentiometercoil 396 at all times since it is connected across the transmissionconductors 289 andV 291. When the horizontal or azimuth drive motor 57is operated in accordance with the movement of the target control, thegenerator will generate a current in proportion to the speed of movementof the motor which is moving the target 43 horizontally. This energizesthe polarized relay 415 to make contact with either the conductor 421 or423. This causes the operation of the motor 376 in one direction or theother. The screw 378 is threaded in such a manner that the slide 380will carry the movable contact 398 under such conditions to the pointwhere the voltage drop between the conductor 405 and the contact 398 isequal to the voltage generated by the generator 63 so that no currentwill tloW through the polarized relay 415. This arrangement will causethe slide 380 to follow the speed of the generator and to compensate fortheY speed of the target in the horizontal direction.

A similar arrangement is provided for the potentiometer coil 401,movable contact 403 and the zenith compensating motor 386. The middlepoint of the potentiometer coil 401 is connected by a conductor 429 to aforward-backward control 431 provided with a movable contact ringconnected directly to the movable contact 326 which is rotated by theazimuth target motor 57. The coil of this forward-backward control 431is connected by the conductor 433 to the commutator brush 435 of thegenerator 55 which is moved by the zenith drive motor 51. The otherbrush 437 of this generator is connected by the conductor 439 with theelectromagnet coil 441 of the polarized relay 443. This polarized relayis also one which disconnects the circuits when deenergized but whenenergized makes contact with either the conductor 447 or conductor 449.The conductor 447 connects to one set 451 of the iield windings whilethe conductor 449 connects to the other set 453 of the ield windingscausing the rotation of the motor 386 in opposite direction dependingupon the position of the. polarized relay 443. The one end of the coilof the forward-backward control 431 is connected by a conductor 455 tothe conductor 439. The forwardbackward control 431 varies the flow ofcurrent provided by the generator 55 in accordance with the direction ofthe turret with respect to the line of flight of the airplane upon whichit is mounted.

The operation of the vertical drive motor 51 causes the generator 55 togenerate a current in opposition to the vertical speed of the target 43.This current is compensated for direction by the backward-forwardcompensator 431 controlled by the rotational position of the turret. Thecurrent is used to operate the polarized relay 443 which in turncontrols the operation of motor 386 `in either direction. The verticalscrew 388 is so threaded that when the motor 386 turns it will continueto turn and move the contact 403 in such a direction that the voltagedrop between the conductor 429 and the movable contact 403 equals thevoltage generated by the zenith target generator 55 as compensated forby the compensator 431. The zenith target generator 55 andthe azimuthtarget generator 63 have such a generating rate that the above describedcircuit and mechanism will move the cam 366 to the proper position bothvertically and horizontally to compensate for the vertical andhorizontal speed of the target so that when the sight 348 is properlytrained upon the target 43, the cam 366 will engage the cam 364 of theswitch mechanism 344 to close the switch 344. llf the trigger 128 shouldhappen to be depressed to close the switch 328 then both mechanisms 342and 346 would count each impulse in the circuit controlled by thepulsator 336. If the trigger 128 is not depressed, the pulsator 336 willnot operate to provide impulses. If the cam switch 344 is not closedonly the shot meter 342 will be operated.

While I have described the disclosure as applied principally to agunnery trainer it is obvious that many features can be applied directlyto a gun turret or gun moving mechanism including particularly the drivemechanism and the compensating drive therefrom.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

l. A'gunnery trainer' comprising in combination, a simulated gun mountedupon a gun yoke, a gun control including trigger simulating means, gundrive means responsive to said gun control for positioning said gun andyoke, a target arm carrying a target, a remote target control, targetdrive means responsive to said target control for positioning saidtarget arm, a sight carried by said gun yoke for viewing said target,the construction and arrangement being such that said sight may betrained upon said target and caused to follow the movement of saidtarget by operation of said gun drive means, sight compensating meansresponsive to said gun drive means for adjusting the position of saidsight on said gun yoke relative to said gun to provide a lead angle forsaid gun, electric circuit means responsive to said trigger simulatingmeans for simulating the firing of shots, iirst counting means forcounting in proportion to the number of shots fired, a switch carried bysaid gun yoke, a cam carried by said target arm for actuating saidswitch, cam compensating means responsive to said target drive means foradjusting the position of said cam on said target arm such that said camwill engage said switch when said gun hasv the proper lead anglerelative to said target, and second counting meansv for counting inproportion to the number of shots fired While said switch is actuated bysaid cam.

2. In a gunnery trainer, the combination with a simulated gun, a guncontrol including trigger simulating means, gun drive means responsiveto said gun control for positioning said gun, a sight, and compensatingmeans responsive to said gun drive means for positioning said sightrelative to said gun in accordance with the movement of said gun drivemeans to provide a lead angle between said gun and said sight, of atarget, a target control, target drive means responsive to said targetcontrol, electric circuit means subject to the control of said triggersimulating means for simulating the firing of shots, a first counterenergized by said circuit means for counting in proportion to the numberof shots red, a switch supported in Xed relationship to said gun, a camfor actuating said switch, compensating means responsive to said Vtargetdrive means for supporting said cam in compensating relationship to saidtarget such that said cam will actuate said switch when said gun is atthe proper lead angle relative to said target, and a second countersubject to the control of said switch and said trigger simulating meansfor counting in proportion to the number of shots tired while said camactuates said switch.

3. A gunnery trainer comprising in combination, means simulating a gun,a gun control, a gun drive responsive to said gun control forpositioning said simulated gun, a target arm carrying a target, a targetcontrol, a target drive responsive to said target control forpositioning said target, an electric circuit for simulating the firingof shots, trigger simulating means for actuating said circuit to eiectthe firing of shots, a counter for counting shots fired, switch meansoperating between said target arm and said gun simulating means forconnecting said counter in said electric circuit when said simulated gunis at the correct lead angle relative to said target, means responsiveto said target drive for adjusting said switch means so as to vary thelead angle at which said switch means wiil operate in accordance withthe motion of said target, a sight, and means responsive to said gundrive for positioning said sight relative to said simulated gun suchthat when said sight is trained on said target said gun will have a leadangle relative to said sight determined by the movement of said gundrive, the construction and arrangement being such that when said guncontrol is manipulated so as to cause the sight to follow the movementsof said target said switch means will operate to cause the simulatedshots then red to be counted,

References Cited in the le of this patent UNITED STATES PATENTS

